This invention relates generally to insulating glass windows, and more particularly to a window comprising two glass sheets separated slightly from each other and bonded to opposite sides of a moisture-absorbing spacer frame made from a plastic strand. It is particularly useful in a vertically adjustable side window for a motor vehicle.
Insulating glass windows for vehicles are known in the art. See, for example, DE-OS 35 17 581. Insulating glass panes used for this purpose generally consist of two relatively thin individual glass panes each 2 to 3 mm thick. This is to insure that the weight of the insulating glass pane remains within acceptable limitations. In addition, in view of the structural configuration of the vehicle body and the window frame, it is desirable to provide a very thin intermediate air space between the two individual glass panes on the order of 2 to 4 mm. In order to meet this requirement, the spacer frame's cross section must also exhibit this width.
When a very thin air space is desired between the glass panes, it is not possible to produce the spacer frame from a hollow metal section such as that used with insulating glass panes having substantially greater distances between the individual glass panes. This creates a problem since it is desirable to place moisture absorbing material in the intermediate air space and this is ordinarily done by placing such material in the hollow space of the metal spacer frame. Attempts have been made to solve this problem by using a moisture-absorbing plastic strand along the pane circumference that functions as a spacer frame. See, for example, DE 25 55 383 B2 and DE 25 55 384 B2.
However, the moisture-absorbing means in the plastic strand cannot arbitrarily be increased if the plastic strand is to retain its functions as an adhesive that bonds the two glass panes together and as a seal that prevents moisture from penetrating or diffusing into the intermediate air space. At the same time, the cross-sectional width of the bonding strand must be the same as the distance between the two glass panes. Since very thin insulating glass panes require the cross section of the plastic strand forming the spacer frame to be correspondingly small, the total amount of drying agent contained in the plastic strand between very thin insulating panes is also relatively small. Therefore, there is a danger that the life of such insulating glass panes will be limited due to the small amount of drying agent available. This danger is especially great in the case of auto glass panes since they are subjected to varying outside air pressure which increases the diffusion processes through the spacer frame and the sealing compound.
Thus, an auto window is desirable comprising two sheets of glass separated by and bonded to a bonding strand which has an increased moisture-absorbing ability while retaining its required narrow cross-sectional width.